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1.
Aust Dent J ; 69(2): 124-138, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38131257

RESUMO

BACKGROUND: Clinical practitioners may have become familiar with the rapid transformation of dental composites. However, they may not scientifically understand the factors influencing the mechanical and physical properties. Scientific knowledge of filler-resin interaction can significantly improve clinical understanding of resin composites. Several independent studies have examined the mechanical and physico-mechanical properties of dental resin composites; however, no comprehensive study has examined the influence of fillers and resin materials on the physico-mechanical properties of both self-cure and dual-cure composites. METHODS: This study performed investigations on the physico-mechanical behaviour of four commercially available dual-cure dental composites (Bioactive, Fill Up!, Surefil One, Cention N) and two commercially available self-cure dental composites (Stela Capsule and Stela Automix). Test specimens for flexural and compressive strength, microhardness, fracture toughness, and hydrolytic behaviour were prepared and tested as per respective standards. The data sets were statistically analysed using one-way ANOVA and Tukey's post-hoc comparison. RESULTS: There was a substantial variation in flexural strength and modulus values in this study, ranging from 32.0 to 113.4 MPa and 2.36 to 12.07 GPa, respectively. Similarly, there were significant differences in compressive strength between the materials in this study, ranging from 119.3 to 223.5 MPa. The highest fracture toughness value was found to be 1.41 MPa.m0.5, while the lowest value was 0.43 MPa.m0.5. Variations in surface microhardness were significant (24.11-68.0 N/mm2), which correlated with the filler content. Water sorption and solubility demonstrated high variations among materials, with Surefil One exceeding ISO 4049 thresholds significantly. CONCLUSIONS: A linear correlation can be established between surface microhardness (HV) and flexural and compressive moduli, as well as filler content (wt.%). However, both flexural and compressive strengths are impacted by the resin's constituent monomers and the resin-filler matrix's cross-linking capability. Additionally, factors such as filler size, shape, and the cross-linking ability of the resin-filler matrix play a crucial role in fracture toughness and the propagation of cracks within the restoration. Also, resin monomers and filler particle size affect the hydrolytic degradation characteristics of composites, which can also affect their mechanical properties. © 2023 Australian Dental Association.


Assuntos
Resinas Compostas , Teste de Materiais , Resinas Compostas/química , Resistência à Flexão , Dureza , Força Compressiva , Análise do Estresse Dentário
2.
Heliyon ; 9(2): e13571, 2023 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-36865476

RESUMO

Betel-nut leaf plate fiber (BLPF) is a lingo-cellulosic natural fiber that can be used to make eco-friendly and biodegradable blended or hybrid fabric with Banana fiber. In the world of organic textiles, naturally dyed BLPF-Banana fiber can be used for wearable products and satisfy health and hygiene issues. BLPF and Banana fiber can be good natural fibers for hybrid fabrics despite being considered waste materials. In this research work, both of the fibers were pretreated carefully to get the desired fineness, color, flexibilities, etc., which are necessary to manufacture fabric. BLPF-Banana woven (1 × 1) hybrid fabric was developed where 12 Ne Banana yarns were used in the warp direction, and 20 Ne BLPF yarns were used in the weft direction and it was dyed naturally with Turmeric. Evaluations of different physico-mechanical properties; tensile strength (854.9 N), tearing strength (14.5 N), stiffness (3.1 N), crease recovery (75° angle), and fabric thickness (1.33 mm) of naturally dyed BLPF-Banana blended fabric were tested, and found satisfactory. SEM, FTIR, and Water vapor transmission tests were also conducted in this study. It attempted to turn the wastages into an asset to make a unique biodegradable BLPF-Banana hybrid fabric by blending two types of natural fibers with the help of natural dyeing substance; it could be a god replacement for synthetic blended fabric.

3.
Polymers (Basel) ; 14(23)2022 Dec 05.
Artigo em Inglês | MEDLINE | ID: mdl-36501712

RESUMO

An epoxy resin modified with polysulfone (PSU) and active diluent furfuryl glycidyl ether (FGE) was studied. Triethanolaminotitanate (TEAT) and iso-methyltetrahydrophthalic anhydride (iso-MTHPA) were used as curing agents. It is shown that during the curing of initially homogeneous mixtures, heterogeneous structures are formed. The type of these structures depends on the concentration of active diluent and the type of hardener. The physico-mechanical properties of the hybrid matrices are determined by the structure formed. The maximum resistance to a growing crack is provided by structures with a thermoplastic-enriched matrix-interpenetrating structures. The main mechanism for increasing the energy of crack propagation is associated with the implementation of microplasticity of extended phases enriched in polysulfone and their involvement in the fracture process.

4.
Materials (Basel) ; 15(22)2022 Nov 16.
Artigo em Inglês | MEDLINE | ID: mdl-36431612

RESUMO

The cement industry generates very large amounts of CO2 into the atmosphere. In recent years, there has been a search for alternative cementitious materials and micro-fillers that could partially or fully replace cement in cement composites without compromising their durability. This paper investigates the possibility of using brick powder (BP) and clay powder (CP) as a partial replacement for cement (up to 20% by weight) in cement paste. The raw materials were characterized, and the physical and mechanical properties of the modified cement pastes were studied, as well as their resistance to a short-term thermal shock at 250 °C. The study was supplemented by intelligent modelling of compressive strength using the support vector machine (SVM) algorithms. The results indicated a significant increase in tensile strength (up to 100%) and an increase in thermal resistance of cement pastes modified with BP and CP. The proposed SVM model had high accuracy (R2 = 0.90), indicating its suitability to predict the compressive strength of the modified cement matrix. This study complements the knowledge in the field of inter alia, the effect of a short-term thermal shock at elevated temperature on the properties of BP and CP modified cement paste, and the effect of BP, which, due to its grain size, plays more the role of a microfiller than a pozzolanic additive.

5.
Materials (Basel) ; 15(16)2022 Aug 19.
Artigo em Inglês | MEDLINE | ID: mdl-36013850

RESUMO

The construction industry must meet current environmental requirements, mostly those pertaining to the reduction in construction and demolition waste and the consumption of raw materials. The use of recycled concrete aggregates can be part of the solution, but one question that arises is how many times recyclables can be recycled. This unknown involves other related queries regarding the properties and possible uses of repeated recycled concrete aggregates. This research is derived from the precast concrete industry, where multi-recycling is a pressing need. From good-quality parent concretes, three cycles of recycled concrete aggregates were produced and analysed. The final results are promising due to the good quality of the recycled and multi-recycled concrete aggregates obtained. Not only can they be used in low-level applications (backfilling) as usual, but they can also be used for more demanding purposes, such as graded aggregates, cement-treated road bases and concrete pavements. Their use in structural concrete is feasible, but it will be dependent on the water absorption level and the amount of recycled aggregate substitution. This research proves the viability of multi-recycled concrete aggregates with all of the associated environmental benefits.

6.
Polymers (Basel) ; 14(11)2022 May 28.
Artigo em Inglês | MEDLINE | ID: mdl-35683869

RESUMO

Highly porous composite poly(vinyl alcohol) (PVA) cryogels loaded with the poly(3-hydroxybutyrate) (PHB) microbeads containing the drug, simvastatin (SVN), were prepared via cryogenic processing (freezing-storing frozen-defrosting) of the beads' suspensions in aqueous PVA solution. The rigidity of the resultant composite cryogels increased with increasing the filler content. Optical microscopy of the thin section of such gel matrices revealed macro-porous morphology of both continuous (PVA cryogels) and discrete (PHB-microbeads) phases. Kinetic studies of the SVN release from the drug-loaded microbeads, the non-filled PVA cryogel and the composite material showed that the cryogel-based composite system could potentially serve as a candidate for the long-term therapeutic system for controlled drug delivery. Such PHB-microbeads-containing PVA-cryogel-based composite drug delivery carriers were unknown earlier; their preparation and studies have been performed for the first time.

7.
Artigo em Inglês | MEDLINE | ID: mdl-35599290

RESUMO

The usage of waste for the development of sustainable building materials has received an increasing attention in socio-eco-environment spheres. The rice husk ash (RHA) produced during burning of rice husk and the ever-increasing plastic wastes are useless causing detrimental effects on the environment. This research supports the idea of sustainability and circular economy via utilization of waste to produce value-added products. This research explores the potential of waste plastics, RHA, and silica sand as thermoplastic composite materials. The different composite samples were prepared through waste plastics which includes low- and high-density polyethylene and polypropylene with incorporation of RHA and silica sand in proportions. The study investigates the effect of filler/polymer in 30/70, 20/80, and 10/90 (wt. %) on the workability of the developed composite materials. The workability of the composites was found to improve with filler reinforcement. The experimental results showed the maximum density of 1.676 g/cm3 and mechanical strength of 26.39, 4.89, and 3.25 MPa as compressive, flexural, and tensile strengths, respectively. The minimum percentage of water absorption was 0.052%. The wear tests resulted in a minimum abrasive and sliding wear rate of 0.03759 (cm3) and 0.00692 × 10-6 kg/m. The correlations between wear mechanisms and responses were morphologically analyzed. The developed composites verify the feasibility of RHA and plastics waste as a cost effective and environmentally competent product. The results and discussions provided a direction for the future research on sustainable polymeric composite materials.

8.
Environ Sci Pollut Res Int ; 29(47): 71936-71947, 2022 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-35608771

RESUMO

Within the scope of the present study, the marble cutting waste, which is an industrial waste of different sizes (< 75 µm and < 150 µm), was incorporated into the clay structure at various rates and a total of 36 series bricks were produced. The brick mixtures were prepared by the semi-dry molding method and the brick specimens were sintered for three temperatures (850 °C, 950 °C, and 1050 °C). The fired bricks containing marble cutting waste with a lower particle size (75 µm) have higher compressive strength. However, all samples produced can meet the relevant standard requirements in terms of compressive strength. Thermal conductivity decreased from 1.008 to 0.775 W/mK with the incorporation of marble cutting waste, a decrease of approximately 23.11%. The effects of grain size, firing temperature, and marble cutting waste concentration on the quadratic model were statistically determined by variance analysis (ANOVA). According to statistical findings, the order of importance of design factors for brick properties (except for compressive strength) is marble cutting waste > firing temperature > particle size. For compressive strength, the most dominant factor is amount of marble cutting waste, followed by particle size and firing temperature, respectively. Consequently, the results suggest that marble cutting waste does not need to be reduced to smaller particle sizes to improve the fired clay brick properties.

9.
Heliyon ; 8(4): e09287, 2022 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-35497028

RESUMO

The hybridization effect of agro-waste pineapple leaf fibre (PALF) and jute fibre as reinforcement in linear low-density polyethylene (LLDPE) composites was investigated in this work. The samples were fabricated by using the heat press compression moulding. The effect of gamma irradiation on composite physico-mechanical properties was also investigated in order to determine the best gamma dose among 2.50, 5.00, 7.50, and 10.00 kGy. The composite sample containing 40% PALF and 60% jute (with a total weight of 50% fibres) demonstrated the most feasible tensile strength (33.36 ± 0.59 MPa), tensile modulus (1494.41 ± 10.94 MPa), elongation at break (50.92 ± 0.77%), bending strength (82.58 ± 0.49 MPa), bending modulus (4932.46 ± 96.12 MPa), and impact strength (34.38 ± 0.42 kJ/m2) at 7.50 kGy irradiation. Thermogravimetric analysis (TGA) determined the thermal performance of the samples. Scanning electron microscopy (SEM) images at the tensile fracture surfaces of composites revealed the interfacial interaction between reinforcement fibres and matrix.

10.
Materials (Basel) ; 15(6)2022 Mar 10.
Artigo em Inglês | MEDLINE | ID: mdl-35329492

RESUMO

The aim of the present study is to link the thermal expansion, spectral reflectance, and physico-mechanical aspects of different types of commercial granitic rocks with their mineralogical and chemical composition. The granitic rock types were characterized using several analyses, including petrography, chemical, mineralogical, and thermo-gravimetrical analysis using XRF, XRD, and TG/DTG/DSC techniques. The rock types were subjected to several performance tests, such as tests of their thermal expansion, spectral reflectance, and physico-mechanical properties. The results revealed that quartz, albite, and potash feldspar with minor amounts of mica (biotite/muscovite/annite) are the main mineralogical constitutes, in addition to some alteration minerals, such as kaolinite, saussorite, and prehnite. The studied granitic rocks were classified as monzogranite/syenogranite of high K-calc-alkaline and peraluminous characters and are related to late- to post-collisional settings. The thermogravimetrical analysis revealed that the overall mass loss over the whole temperature range up to 978 °C did not exceed 3% of the initial weight for all studied rocks. The results of thermal expansion revealed that the maximum change in linear thermal expansion for all rock types did not exceed 0.015% of their initial lengths at an unusual air temperature of 50 °C. The spectral analysis revealed that iron and hydroxyl ions are the main spectral absorption features that appeared in the VIS-NIR and SWIR regions, in addition to the appearance of the common and distinctive absorption peaks of the main mineral composition. Furthermore, the spectral reflectance demonstrated that the granitic rock types of low iron oxide content achieved a high reflectivity percent in the VIS-NIR and SWIR spectral regions compared with those of high iron content. As a general trend, the granitic rock types of high iron content and/or lower quartz content exhibited a high performance regarding their physical and mechanical properties, such as water absorption, apparent porosity, bulk density, compressive strength, and abrasion resistance. The results of water absorption, density, strength, and abrasion resistance of the studied granitic rocks are in the range of 0.14-0.31%, 2582-2644 kg/m3, 77.85-222.75 MPa, and 26.27-55.91 Ha, respectively, conforming to the requirements of ornamental stones according to the ASTM standard.

11.
Polymers (Basel) ; 14(3)2022 Jan 28.
Artigo em Inglês | MEDLINE | ID: mdl-35160532

RESUMO

In this paper, low-temperature extrusion of ground tire rubber was performed as a pro-ecological waste tires recycling method. During this process, ground tire rubber was modified with constant content of dicumyl peroxide and a variable amount of elastomer (in the range: 2.5-15 phr). During the studies, three types of elastomers were used: styrene-butadiene rubber, styrene-ethylene/butylene-styrene grafted with maleic anhydride and ethylene-octene copolymer. Energy consumption measurements, curing characteristics, physico-mechanical properties and volatile organic compounds emitted from modified reclaimed GTR were determined. The VOCs emission profile was investigated using a passive sampling technique, miniature emission chambers system and static headspace analysis and subsequently quantitative or qualitative analysis by gas chromatography. The VOCs analysis showed that in the studied conditions the most emitted volatile compounds are dicumyl peroxide decomposition by-products, such as: α-methylstyrene, acetophenone, α-cumyl alcohol, methyl cumyl ether, while the detection level of benzothiazole (devulcanization "marker") was very low. Moreover, it was found that the mechanical properties of the obtained materials significantly improved with a higher content of styrene-butadiene rubber and styrene-ethylene/butylene-styrene grafted with maleic anhydride while the opposite trend was observed for ethylene-octene copolymer content.

12.
Environ Sci Pollut Res Int ; 29(18): 26631-26647, 2022 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-34859346

RESUMO

The influence of lightweight expanded clay aggregate (LECA) on the physico-mechanical properties and microstructure of geopolymer mortar containing slag binder alkali-activated with sodium silicate solution before and after exposure to thermal loads was investigated. In the current procedure, siliceous sand was partially substituted with LECA fine aggregate at levels of 0%, 25%, 50%, 75%, and 100%, by volume. The effect of LECA on the performance before exposure was evaluated by measuring flowability, water absorption, bulk density, thermal conductivity, and compressive strength. To monitor the behavior after exposure, a batch of specimens having the same composition was subjected to high temperatures in the range of 400-1000 °C for 2 h with a heating rate of 5 °C/min. In a similar fashion, mass loss and residual compressive strength were determined. New phase-based geopolymers were examined using Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The findings indicated that the incorporation of LECA up to 100% as an alternative to siliceous sand aggregate in geopolymer mortar has an adverse effect on compressive strength and water absorption, but has a positive effect on workability, thermal conductivity, and relative strength after exposure to elevated temperatures.


Assuntos
Temperatura Alta , Areia , Argila , Temperatura , Água/química
13.
Environ Sci Pollut Res Int ; 29(1): 146-157, 2022 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-34409534

RESUMO

This work concerns the reuse of treated wastewater from Er-Rachidia wastewater treatment plant (WWTP) in the mixing of ordinary C20/25 concrete, to reduce the overexploitation of non-potable groundwater, avoid its discharge into watercourses and reduce the risk of environmental pollution due to its mineral and organic matter load. In this respect, three types of mixing water were used in this study: drinking water (DW), non-potable groundwater (GW), and treated wastewater (TW). The results recorded for each type of mixing water, in the fresh and hardened state of concretes, were compared with the requirements of the standards. The obtained results show that the treated wastewater does not have any adverse effect upon the quality of the concrete; it has shown an improvement of the mechanical strength from the first stage, a similar density, setting time, and porosity and a slight decrease of the workability compared with the control concrete. A one-way analysis of variance (ANOVA) of the mechanical performance of concrete at different cure times (7, 14, 28, and 90 days) has shown that there is no significant decrease in the mechanical performance of concretes based on TW and GW compared with concretes formulated with DW. Through this study, the substitution of drinking water by treated TW and GW will help to minimize the footprint of construction materials on natural resources. From a point of view of the mechanical performance, TW and GW improve the mechanical performance of concrete. Additionally, it makes wastewater treatment plants more economically attractive and contributes to sustainable development.


Assuntos
Água Potável , Água Subterrânea , Purificação da Água , Materiais de Construção , Águas Residuárias
14.
Polymers (Basel) ; 13(21)2021 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-34771348

RESUMO

Among the main biodegradable food packaging materials, poly-lactic acid (PLA) is a commercially successful polymer used notably in the food packaging industry. In this study, active PLA films containing different percentage of anise essential oil (AE) (0, 0.5, 1 and 1.5% v/v) were developed, and characterized by physical, mechanical and antibacterial analysis. Based on physical examinations, thermal stability of PLA/AE films was greater than the neat PLA film, and the minimum water vapor permeability (WVP) was recorded for PLA/0.5AE film (1.29 × 10 11 g/m s), while maximum WVP was observed for PLA/1.5AE (2.09 × 1011 g/m s). Moreover, the lightness and yellowness of the composites were decreased by the addition of AE. For the PLA composites with 1.5% AE, the tensile strength decreased by 35% and the elongation break increased by 28.09%, comparing to the pure PLA. According to the antibacterial analysis, the minimum inhibitory concentrations of PLA/AE film were 5 to 100 mg/mL and the active composite could create visible inhibition zones of 14.2 to 19.2 mm. Furthermore, the films containing AE inhibited L. monocytogenes and V. parahaemolyticus in a concentration-dependent manner. The confirmation of the success of the incorporation of EOs into the PLA films was further evaluated using principal component analysis, where positive results were obtained. In this context, our findings suggest the significant potency of AE to be used as an antibacterial agent in active food packaging.

15.
Molecules ; 26(3)2021 Jan 28.
Artigo em Inglês | MEDLINE | ID: mdl-33525731

RESUMO

In the current context of green mobility and sustainability, the use of new generation natural fillers, namely, α-cellulose, has gained significant recognition. The presence of hydroxyl groups on α-cellulose has generated immense eagerness to map its potency as filler in an elastomeric composite. In the present work, α-cellulose-emulsion-grade styrene butadiene rubber (E-SBR) composite is prepared by conventional rubber processing method by using variable proportions of α-cellulose (1 to 40 phr) to assess its reinforce ability. Rheological, physical, visco-elastic and dynamic-mechanical behavior have clearly established that 10 phr loading of α-cellulose can be considered as an optimized dosage in terms of performance parameters. Morphological characterization with the aid of scanning electron microscope (SEM) and transmission electron microscopy (TEM) also substantiated that composite with 10 phr loading of α-cellulose has achieved the morphological threshold. With this background, synthetic filler (silica) is substituted by green filler (α-cellulose) in an E-SBR-based composite. Characterization of the compound has clearly established the reinforcement ability of α-cellulose.


Assuntos
Butadienos/química , Celulose/química , Elastômeros/química , Estirenos/química , Resinas Compostas/química , Emulsões/química , Dióxido de Silício/química
16.
Materials (Basel) ; 13(22)2020 Nov 13.
Artigo em Inglês | MEDLINE | ID: mdl-33202868

RESUMO

New ceramic formulations based on scheelite tailing were developed, and their potential in the ceramic industry was evaluated. Green bodies with different contents of scheelite tailing (0-8 wt%) were sintered (1150 °C, 1200 °C, and 1250 °C) and characterized in terms of the main mineralogical phases, microstructure, and physico-mechanical properties. The mullite was the main phase identified in all sintered temperatures. This result was also ratified with the aid of scanning electron microscope (SEM) images, in which small needles of the mullite were detected. The presence of mullite is required because it contributes to increasing the mechanical resistance of the material. The physico-mechanical properties measured (water absorption, linear shrinkage, apparent porosity, and flexural strength) were compared to the ISO 13006, and the samples sintered at 1150 °C presented potential to be used as semi-stoneware, while those sintered at 1200 °C and 1250 °C can be employed stoneware and porcelain tiles, respectively.

17.
Carbohydr Polym ; 250: 117011, 2020 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-33049872

RESUMO

A comparative study on the morphology and physico-mechanical properties of cellulose nanofibrils (CNF) and lignocellulose nanofibrils (LCNF) produced using a pilot-scale ultra-refining facility in the form of slurries and films was conducted. Suspensions and films of CNF and LCNF at different fines contents from 50% to 100% were prepared from bleached kraft pulp and old corrugated container (OCC) feedstock, respectively. We showed that the effect of film density on mechanical properties of CNF and LCNF films can outweigh the effect of fines content (or degree of fibrillation) and consequently an equally strong and stiff film can be produced from lower grades of CNF or LCNF at higher densities. After density normalization, particle size was found to be the main determining factor. Finally we conclude that a CNF or LCNF suspension with 70 % fines will yield films as strong and stiff as the materials with 100 % fines providing an opportunity for cost reduction.

18.
Polymers (Basel) ; 12(8)2020 Aug 11.
Artigo em Inglês | MEDLINE | ID: mdl-32796658

RESUMO

In the present work, and for the first time, totally biosourced low-density particleboards were produced using cardoon particles (a no added value by-product from the Portuguese cheese making industry), bound with a potato starch adhesive. Different starch/cardoon ratios (0.6, 0.8, 1 and 1.2) were tested and the effect of different bio-based additives (chitosan, wood fiber and glycerol) on the performance of the adhesive system was evaluated. The best result was obtained for a formulation with a starch/cardoon mass ratio of 0.8, a chitosan/starch mass ratio of 0.05 and a water/starch mass ratio of 1.75. The particleboards produced had a density of 323 kg·m-3, internal bond strength of 0.35 N·mm-2 and thickness swelling of 15.2%. The values of density and internal bond strength meet the standard requirements of general-purpose lightweight boards for use in dry conditions according to CEN/TS 16368 specification. Moreover, the susceptibility of the formulations with best results was established against subterranean termites and one decay fungi.

19.
Int J Biol Macromol ; 160: 971-978, 2020 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-32464211

RESUMO

An active chitosan-based film, blended with the hydrolysable tannin-rich extract obtained from fibrous chestnut wood (Castanea sativa Mill.), underwent a simultaneous engineering optimization in terms of measured moisture content (MC), tensile strength (TS), elongation at break (EB), and total phenolic content (TPC). The optimal product formulation for a homogeneous film-forming solution was sought by designing an empirical Box-Behnken model simulation, based on three independent variables: the concentrations of chitosan (1.5-2.0% (w/v)), extracted powder-form chestnut extract (0.5-1.0% (w/v)) and plasticizer glycerol (30.0-90.0% (w/w); determined per mass of polysaccharide). Obtained linear (MC), quadratic (TS or EB), and two-factor interaction (TPC) sets were found to be significant (p < 0.05), to fit well with characteristic experimental data (0.969 < R2 < 0.992), and could be considered predictive. Although all system parameters were influential, the level of polyol played a vital continuous role in defining EB, MC, and TS, while the variation of the chestnut extract caused an expected connected change in affecting TPC. The component relationship formula of chemical mixture fractions (1.93% (w/v) of chitosan, 0.97% (w/v) chestnut extract and 30.0% (w/w) of glycerol) yielded the final applicable material of adequate physico-mechanical properties (MC = 17.0%, TS = 16.7 MPa, EB = 10.4%, and TPC = 19.4 mgGAE gfilm-1). Further statistical validation of the concept revealed a sufficient specific accuracy with the computed maximal absolute residual error up to 22.2%. Herein-proposed design methodology can thus be translated to smart packaging fabrication generally.


Assuntos
Materiais Biocompatíveis/química , Quitosana/química , Embalagem de Alimentos , Membranas Artificiais , Algoritmos , Fenômenos Químicos , Embalagem de Alimentos/métodos , Fenômenos Mecânicos , Modelos Teóricos , Peso Molecular , Espectroscopia de Infravermelho com Transformada de Fourier
20.
Polymers (Basel) ; 12(3)2020 Mar 11.
Artigo em Inglês | MEDLINE | ID: mdl-32168761

RESUMO

In this study, four types of waste bamboo fibers (BFs), Makino bamboo (Phyllostachys makinoi), Moso bamboo (Phyllostachys pubescens), Ma bamboo (Dendrocalamus latiflorus), and Thorny bamboo (Bambusa stenostachya), were used as reinforcements and incorporated into polypropylene (PP) to manufacture bamboo‒PP composites (BPCs). To investigate the effects of the fibers from these bamboo species on the properties of the BPCs, their chemical compositions were evaluated, and their thermal decomposition kinetics were analyzed by the FlynnWallOzawa (FWO) method and the Criado method. Thermogravimetric results indicated that the Makino BF was the most thermally stable since it showed the highest activation energy at various conversion rates that were calculated by the FWO method. Furthermore, using the Criado method, the thermal decomposition mechanisms of the BFs were revealed by diffusion when the conversion rates (α) were below 0.5. When the α values were above 0.5, their decomposition mechanisms trended to the random nucleation mechanism. Additionally, the results showed that the BPC with Thorny BFs exhibited the highest moisture content and water absorption rate due to this BF having high hemicellulose content, while the BPC with Makino BFs had high crystallinity and high lignin content, which gave the resulting BPC better tensile properties.

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